Using the Speedstack HDI Navigator to document pcb stack up with coated and uncoated areas

Question:
Is it possible to model a pcb stackup where some areas are coated with resist and other areas deliberately left uncoated?
– Speedstack HDI customer

Answer:
Very easily – with the Speedstack HDI Navigator.

Speedstack Navigator

In this note you will see how the Speedstack HDI Navigator can document a PCB stackup where the board includes areas that are coated with photoresist and surface traces that remain exposed.

First, consider each finished sub-stack in Speedstack HDI:

Uncoated stack

Coated stack

Start by creating the uncoated pcb stackup in the Stack Editor, then press F4 to open the Speedstack HDI Navigator:

Uncoated stack area

This "Master" stack represents the uncoated area; right click the Navigator and use the Addstack command to add a copy of the Master and name it "Coated". Click the new stack and return to the Stack Editor to add the photoresist and ident layers – the Navigator should display both areas as separate stacks (below).

Use Speedstack HDI's goal seeking facility to arrive at the trace widths for the two structures:

Uncoated Layer 1 in Stack Editor

Coated Layer 1 in Stack Editor

Speedstack HDI Navigator opens up not only the
capability of documenting flex-rigid stacks but also allows
you to document specialized pcb stackups. In the above example our
customer needed to produce a board which had areas
intentionally free from resist on the finished board. This
application of Speedstack HDI would be equally applicable should
a fabricator wish to predict the impedance of surface traces
on a part finished board prior to the application of resist.

Contact Polar now and discover the benefits of documenting
and designing your PCB stack up with
Speedstack HDI.